Apparatus for coating of objects using a porous resilient matrix

ABSTRACT

An apparatus for applying a coating to an object includes a pair of reciprocating members which each include a porous resilient pad mounted for movement toward and away from each other. The apparatus includes a coating supply system for supplying coating to the resilient pads. The pads have a movement sequence from an initial rest position where the pads are spaced apart from one another to a coating loading position where the pads are in physical contact and have a degree of compression with each other to load the coating onto the pads, then the pads are moved to an intermediate rest position with the pads spaced apart an the object to be coated is moved between the pads. The sequence then includes a coating delivery position where the pads are in physical contact with each other and the object so that the pads have a degree of compression with each other and the object thereby applying the coating to the object.

This is a division of application Ser. No. 08/509,395, filed Jul. 31,1995, now abandoned.

FIELD OF INVENTION

This invention relates to the coating of objects and more particularlyrelates to methods and apparatus for applying lubricants to medicaldevices such as over-the-needle peripheral venous catheters, hypodermicneedles, blades and the like.

Background of the Invention

Medical devices are often assembled from components formed from manydifferent materials. It often is necessary to apply a coating of alubricant to one or more of the components so that a component of onematerial will readily slide against a component of another material.Examples of this type of application are catheters with guidewires,over-needle catheters, syringe plunger stopper within a syringe barrel,needles for penetration of blood collection tube stoppers and the like.In other medical device applications, a lubricant is applied to a deviceto ease its penetration into the body. Examples of these applicationsare surgical blades, hypodermic needles, peripheral venous catheters andthe like.

In all of these medical device lubrication applications, there arestrict requirements on the amounts of lubricant, the uniformity of theapplication and a need to avoid contamination of the device with foreignmaterial other than the lubricant. A further requirement on applicationof lubricant results from the high volume production requirements oftenresulting in the use of high speed assembly equipment. Thus, anylubricant application must be precise and compatible with high volumeproduction.

Currently, a commonly used lubricant for medical devices is "silicone,"i.e., polydimethyl siloxane having a Brookfield viscosity between about1,000 and 20,000 centistokes (cs). For some applications, the siliconeis applied "neat", i.e., without solvent. An example of neat applicationof silicone to syringe plunger stoppers is disclosed in U.S. Pat. No.5,207,293 to Eden et al. This patent discloses a method and apparatusfor lubricating syringe stoppers by moving the stoppers between a pairof wheels which are positioned partially in a reservoir containinglubricant so that with rotation of the wheels, lubricant is transferredto the stoppers.

Another commonly used neat application method is tumbling a measuredquantity of small parts, such as stoppers, with a measured quantity oflubricant so that the parts acquire a coating of the lubricant.

Silicone lubricant also may be sprayed onto the parts either neat or ina carrier solvent. Neat spraying has been found to work well forinterior surfaces such as inside syringe barrels. Solvent based dippingor spraying is commonly used for coating hypodermic needles andcatheters. Chlorofluorcarbon solvents have proven to be verysatisfactory for the delivery of silicone onto medical devices becausethey are non-toxic, non-flammable, inert, evaporate rapidly withoutleaving residue and are available in very high purity. Unfortunately,because of the belief that chlorofluorocarbon solvents are responsiblefor destruction of ozone in the upper atmosphere, most commonly usedchlorofluorocarbon solvents will no longer be available. Alternatesolvents such as hydrocarbons are flammable, and aqueous based systemsgenerally are not practical for silicones.

Thus, there is a need for an apparatus that is compatible with highproduction volume and capable of uniformly delivering precise quantitiesof lubricant to medical devices.

SUMMARY OF THE INVENTION

An apparatus for applying a coating to an object includes a pair ofreciprocating members each having a porous resilient pad. The membersare mounted for movement toward and away from each other. The apparatusfurther includes a coating supply system for supplying the coating tothe resilient pads. The members have sequential movement positionsstarting from an initial rest position with the resilient pads spacedapart from each other. The movement sequence then includes a coatingloading position where the resilient pads are in physical contact andhave a degree of compression with each other loading the coating intothe pads. There is an intermediate rest position where the pads arespaced apart and the object to be coated is placed between the resilientpads. The movement sequence includes a coating delivery position withthe resilient pads in physical contact with each other and the objectbeing coated, the resilient pads additionally having a degree ofcompression with each other and the object, thereby applying the coatingto the object.

A method for applying a coating to an object includes placing an objectto be coated between two reciprocating members each including aresilient pad mounted for motion toward and away from each other. Theobject is placed between the pads when the pads are spaced apart fromeach other and are loaded with the coating to be applied to the object.The method then includes moving the pads from the pads spaced apartposition to a position where the pads are in physical contact with eachother and the object to be coated so that the pads have a degree ofcompression with each other and the object to be coated thereby applyingthe coating to the object.

The apparatus and method of the present invention provide a precisecoating of neat lubricant to objects such as hypodermic needles,catheters, guidewires and the like. The invention is compatible withhigh volume assembly and can be built into a compact station to be fitinto existing assembly machinery. The method of the present inventionleaves no residual solvent and is simple to practice and maintain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially sectioned perspective view of the preferredapparatus of the present invention for applying a coating to an object;

FIGS. 2A to 2E are partial cross-section schematic views of theapparatus of FIG. 1 along the line 2--2 showing the reciprocatingmembers in the several positions of a movement sequence;

FIG. 3 is a flow chart for a method of applying coating to an objectwith the apparatus illustrated in FIG. 1;

FIG. 4 is a perspective partially sectioned view of another embodimentof the apparatus of the present invention;

FIGS. 5A to 5E are partial cross-sectional schematic views of theapparatus of FIG. 4 along the line 5--5 showing the reciprocating memberin the several positions of a movement sequence;

FIG. 6 is a flow chart for a method of applying coating to an objectwith the apparatus of FIG. 4;

FIG. 7 is a perspective view of another embodiment of the apparatus ofthe present invention;

FIG. 8 is a partial cross-sectional schematic view of the apparatus ofFIG. 7 along the line 8--8;

FIG. 9 is a flow chart for a method of applying coating to an objectwith the apparatus of FIG. 7;

FIG. 10 is a perspective view of a further embodiment of the apparatusof the present invention;

FIG. 11 is a partial schematic view of the apparatus of FIG. 10 alongthe line 11--11; and

FIG. 12 is a flow chart for a method of applying coating to an objectwith the apparatus of FIG. 10.

DETAILED DESCRIPTION

While this invention is satisfied by embodiments in many differentforms, there are shown in the drawings and herein described in detailpreferred embodiments of the invention with the understanding that thepresent disclosure is to be considered exemplary of the principles ofthe invention and is not considered to limit the invention to theembodiments illustrated. The scope of the invention is to be measured bythe appended claims and their equivalents.

Referring to FIGS. 1 and 2A to 2E, an apparatus 10 for coating an object12 of the present invention includes a pair of reciprocating members 14Aand 14B.

In order to facilitate and simplify the present description, thereciprocating members and other parts of apparatus 10 which are presentin pairs are described as symmetrical or identical and are identifiedwith suffixes "A" and "B." For particular applications, such as whenobject 12 is not symmetrical, the present invention is intended toencompass embodiments where parts of the apparatus, herein described inpairs to simplify the description, are not symmetrical or identical.

Reciprocating members 14A and 14B each further include porous resilientpads 16A and 16B. Members 14A and 14B are preferably mounted on a base20 and include drive mechanisms 30A, 30B, and supports 31A, 31B. Pads16A, 16B are mounted for movement toward and away from each other.

Apparatus 10 includes a coating supply system 24 for supplying a coatingto resilient pads 16A, 16B. Preferably resilient pads 16A, 16B eachinclude backing plates 40A, 40B each having a first side 42A, 42B and asecond side 44A, 44B and having a plurality of holes 46A, 46Btherethrough. Pads 16A, 16B each further preferably include reticulatedelastomeric foam layers 48A, 48B having front sides 52A, 52B and backsides 56A, 56B. Back sides 56A, 56B of preferred foam layer 48A, 48Bpreferably are fixedly attached to first sides 42A, 42B of the backingplates.

Members 14A, 14B have a movement sequence schematically illustrated inFIGS. 2A to 2E including an initial rest position with resilient pads16A, 16B spaced apart a distance. "m" from each other. The movementsequence then includes a coating loading position where resilient pads16A, 16B are in physical contact and have a degree of compression witheach other. The degree of compression is determined by comparing thethickness t₁ of pads 16A, 16B in the initial rest position as shown inFIG. 2B to thickness t₂ of pads 16A, 16B in FIG. 2B showing the coatingloading position. The compression of the pads serves to spread thecoating onto pads 16A, 16B. The compression of the pads in the coatingloading step followed by the release of the compression in theintermediate rest position serves to load the coating onto the pads andalso to distribute it. The movement sequence then includes movement toan intermediate rest position where resilient pads are again spacedapart distance "m" as shown in FIG. 2C, allowing placement of the objectto be coated between the pads. The movement sequence then includes acoating delivery position where pads 16A, 16B are in physical contactwith each other and the object being coated. In the coating deliveryposition, the pads have a thickness t₃ and a degree of compression witheach other and the object being coated as represented in FIG. 2D. Thedegree of compression is determined by comparing the ratio of padthickness t₃ with thickness t₁ of the initial rest position. In thecoating delivery position the coating is transferred from pads 16A, 16Bto the object.

Preferably, the degree of compression of pads 16A, 16B in the coatingloading position (t₂ /t₁) is greater than the degree of compression inthe coating delivery position (t₃ /t₁). When the degree of compressionfor coating delivery is less than the degree of compression for coatingloading, results show more uniform and precise transfer of the coatingto the objects being coated.

Preferably, coating supply system 24 includes a reservoir 26 for holdinga coating 27 and a transport system 28A, 28B transporting the coating tothe pads through holes 46A, 46B. Each of the preferred reciprocatingmembers 14A, 14B include drive mechanisms 30A, 30B for reciprocalmovement of the pads through the movement sequence. Preferably apparatus10 includes an object placement system 34 for placing objects 12 betweenthe pads and then removing the objects. Preferred apparatus 10 includesa control system 32 for controlling the coating supply system, thereciprocating member drive system and the object placing system.

The preferred coating supply system includes having coating transportsystem 28A, 28B in fluid communication with second sides 44A, 44B of thebacking plates 40A, 40B so that a relatively constant supply of coatingis maintained at holes 46A, 46B at back sides 56A, 56B of the foamlayers 48A, 48B to load the resilient foam layers.

Control system 32 preferably adjusts coating supply system 28A, 28B sothat there is a sufficient amount of coating available for delivery tothe object. The control system may be mechanical, electromechanical,digital and the like to control the coating delivery, the movement ofthe reciprocating members and the object placement and removal.

A suitable material for the porous foam layer is a reticulatedpolyurethane foam with between about 300 to about 1250 pores per squarecentimeter. In applications where the object to be coated is a medicaldevice such a catheter or a hypodermic needle, a preferred foam is areticulated polyurethane foam which has been permanently thermallysintered from an as-blown height of between about 5 cm to 25 cm to aheight of about 2.5 cm. One skilled in the art of polymeric foamsrecognizes that the thermal sintering is also described as "felting,"and further described as "firmness" or "firmness ratio" of between 2 and10. Thermal sintering involves compressing the foam from the as-blownthickness to a desired thickness, then heating. When the compressionthen is released, the foam retains the compressed thickness. Thissintering has the effect of increasing the density of the foam byreducing the void volume of the pores in the foam.

In the preferred present apparatus, where the object being coated is amedical device such as a catheter, hypodermic needle, a catheter mountedover a hypodermic needle and the like, preferred resilient foam pads16A, 16B have a thickness t₁ between about 0.25 cm to about 2.5 cm andmost preferably between about 0.4 cm to about 0.8 cm. Preferably theobject being coated is placed substantially centrally between theresilient foam pads so that when the pads are in the coating deliveryposition, the object is not substantially deflected. The positioning ofthe object is particularly important when the object being coated ispointed, e.g., a hypodermic needle or a catheter mounted over a needle.If a pointed object is deflected during the coating deliverycompression, there may be a tendency to cause the point to partiallyimbed in one pad or the other, potentially damaging the point, reducingthe service life of the pad and generating undesirable particles.

Preferably the foam has about 10 to about 100 pores per linear cm with afirmness about 4. This preferred foam will have about 85% to about 90%void volume or open pore space. Suitable reticulated polyurethane foams,which are available in a range of firmness between 2 and 10, areavailable as "Foamex SIF felt" from Speciality Polyurethane, 1500 E.Second Street, Eddystone, Pa. 19013 and from E. E. Murray Co., 707Umatilla Street, Denver, Colo. 80204. Other foams having similarproperties are expected to perform satisfactorily. In cases where theobjects to be coated are not medical devices such as needles, blades,catheters and the like, foams having different properties may bedesired. In the preferred coating system, the coating is a lubricant.The apparatus of the invention is suitable for application of othercoatings including, but not limited to, colorants, pesticides and thelike. For these other applications, foams having different compositionand properties may be selected and are included in the scope of theinvention.

In the preferred application, the degree of compression betweenresilient pads 16A, 16B in the coating loading position is greater thanthe degree of compression in the coating delivery position. Thesecompression positions have the effect of reducing the void volume oropen space within the foam When the compression is released from thecoating loading position, the foam returns to the original uncompressedvolume, and at least a portion of the void volume is occupied by thecoating charge. When the foam having a charge of coating is compressedinto the coating delivery position, the foam preferably substantiallyengulfs the object being coated, the coating in the portion of the voidvolume is displaced and transferred to the object being coated.

One skilled in the art of lubricating medical devices recognizes that acoating of polydimethyl siloxane is often used as a lubricant on medicaldevices such as hypodermic needles, scalpels and guidewires made frommetal and on medical devices formed from polymeric materials such ascatheters and probes. The purpose of the lubricant coating is to reducethe sliding friction between the device and tissue or the slidingfriction between one component of the device and another. In almost allapplications of silicone lubricant to medical devices there are twoconflicting requirements governing the amount applied; there should besome uniform minimum amount applied over the entire surface where thesliding friction is to be reduced; and there should not be excess orvisible silicone present on the device. These requirements are often inconflict with each other since polydimethyl siloxane with viscosityabove about 500 cs applied by direct dipping into the neat material,while providing complete coverage, generally results in an undesirableexcess that leads to visible droplet formation. Currently, many siliconelubricant applications rely on use of a volatile solvent carrier todilute the silicone, insure complete coverage of the object and avoiddeposition of excess lubricant. Since polydimethyl siloxane isnon-polar, many solvents otherwise suitable for its delivery are quiteflammable and the medical device industry evolved toward non-flammablechlorofluorocarbon solvents. With the recent recognition of the ozonedepletion problem and its attribution to chlorofluorocarbons, many ofthese solvent based dilution systems for application of silicone are nolonger practical.

As an example, data is presented related to coating four 14 gaugecatheters at a time with 12,500 cs. polydimethyl siloxane (silicone)using the preferred embodiment of the present invention illustrated inFIGS. 1-3. The control used in this study was standard commercialproduct having identical components. The control product was lubricatedwith identical silicone applied using a chlorofluorocarbon solvent basedapplication system. While the preferred embodiment of the presentinvention is well suited for the lubrication of cylindrical objects witha length at least three times longer than their diameter such as needlesand catheters, this example is not to be considered limitative of theinvention to 14 g catheters, rather it is intended to show the utilityand repeatability of the apparatus and method in use over a 24 hourperiod. In this example, the foam used was firmness 4 polyurethaneFoamex. Preferably, pads 16A, 16B are each divided into four sections17A, 17B, the sections being mounted on each reciprocating member tofacilitate easy replacement. Each section 17A, 17B is about 0.635 cmthick (t₁) by 1.27 cm wide by 6.35 cm long giving an uncompressed 16A,16B volume of 41 cm³. The preferred apparatus was set up so that in thecoating loading position pads 16A, 16B were compressed to a thickness of0.158 cm (t₂), a 75% compression (t₂ /t₁ =0.25). In the coating deliveryposition, the pads 16A, 16B were compressed to a thickness of 0.312 cm(t₃), a 50% compression (t₃ /t₁ =0.5). The void volume, i.e., the pores,in the uncompressed state of the foam is about 88% of 41 cm³. When thefoam is under 75% compression, the void volume decreases from 88% to avalue of 76%. When the foam returns to the uncompressed state theincrease in void volume is 12% of 41 cm³ or 4.92 cm³ at least a portionof the void volume then is filled by the preferred coating material,polydimethyl siloxane having a viscosity of 12,500 cs. While thepreferred polydimethyl siloxane has a viscosity about 12,500 cs, thepresent invention is suitable for application of polydimethyl siloxanesor other coatings with Brookfield viscosities at 25° C. between about 10cs to about 1,000,000 cs.

The 24 hour trial run of the apparatus of the present invention wasconducted to apply 12,500 cs polydimethyl siloxane for lubrication tothe 14 g peripheral venous catheters mounted over needles. Samples ofthe coated catheters were taken at regular intervals and the amount ofsilicone lubricant present on their surface was determined byextraction. In the preferred configuration used in the trial, thereciprocating members are mounted so that the pads are vertical with themotion toward and away from each other being horizontal. Preferably, topsurfaces 19A, 19B of the resilient pads are sealed so that when the padsare in the compressed state the coating cannot pass through the topsurface of the pad and pool on surfaces 19A, 19B of the pads. The topsurface may be sealed by adhesive, fusing by heat, ultrasound and thelike. Preferably top surfaces 19A, 19B are fused by pressing against asmooth surfaced heated above the melting point of the polyurethane foamforming a skin. When the apparatus is operating in a steady state,control system 32 is preferably adjusted so that the amount of coatingmaterial delivered to the foam pads is only a slight excess to thedesired amount being applied to the catheters. The slight excess cannotpool on the top surface because of the sealed surfaces 19A, 19B andmigrates to the bottom of the pads where it may be collected withouteffecting the amount present on the catheters. The slight excessdelivery to the pads ensures that the distribution into the pads duringthe coating loading cycle is sufficient to provide substantially uniformcoverage of the object being coated.

The results show that the preferred apparatus of the present inventionwas able to reliably and repeatedly apply 0.30±0.075 mg polydimethylsiloxane to more than 20,000 catheters over a 24 hour period.Comparisons in standard laboratory performance testing for penetrationforce and drag force show generally similar behavior between theseexperimental catheters lubricated by the preferred apparatus of thepresent invention and standard commercial product lubricated byapplication of the same silicone in chlorofluorocarbon solvent.

A constant concern in manufacture of over needle catheters is damage tothe point of the needle during lubrication of the catheter andintroduction of foreign matter onto the catheter or needle point duringlubrication. In the trial, there was overall comparable performance ofthe catheters lubricated by the preferred present invention to standardcommercial product indicating that the lubrication levels werecomparable and that there was no detectable degradation in needle pointquality. Careful microscopic examination showed that there was littleevidence of introduction of particulates resulting from the contactbetween the resilient foam and the catheter. Further, there was noadditional microbial background contamination or bioburden on catheterslubricated in the trial of the preferred apparatus when compared to thestandard commercial product.

Referring now to FIGS. 4-12, alternative embodiments of the coatingapparatus of the present invention are illustrated. In these embodimentsthe coating loading and the coating delivery include compression andrelease of a porous resilient member being loaded with and deliveringcoating to an object. Accordingly, substantially similar componentsperforming substantially similar functions are numbered identically tothose components of the embodiment of FIGS. 1-3 except that thereference characters include hundreds digits to identify thosecomponents in FIGS. 4-12.

In the embodiment illustrated in FIGS. 4-6, apparatus 110 includes areciprocating member 114 with a coating supply system 124 for supplyinga coating to a resilient pad 116. Preferably resilient pad 116 includesa backing plate 140 having a first side 142 and a second side 144 andhaving a plurality of holes 146 therethrough. Pad 116 further preferablyincludes a reticulated resilient foam layer 148 having a front side 152and a back side 156. Back side 156 is preferably fixedly attached tofirst side 142 of the backing plate.

Member 114 has sequential movement positions, illustrated in FIGS. 5A to5E, similar to that described for the embodiment of FIGS. 1-3. In theembodiment of FIGS. 4-6, coating 127 is supplied to resilient pad 116 bya coating supply system 124 from a coating reservoir 126 through acoating transport system 128. In the movement sequence, member 114includes an initial rest position with resilient pad 116 spaced adistance "m" from a fixed member 117 having a resilient surface 119. Themovement sequence then includes a coating loading position withresilient pad 116 in physical contact with and has a degree ofcompression with the fixed member as shown by comparing the thickness t₁of pad 116 in the initial rest position shown in FIG. 5B to thickness t₂of pad 116 in FIG. 5B which shows the coating loading position. Thecompression serves to load and spread the coating into pad 116. Thesequential movement then includes movement to an intermediate restposition shown in FIG. 5C, where resilient pad 116 is again spaced adistance "m" away from fixed member 117. The intermediate rest positionallows placement of object 112 to be coated between resilient pad 116and fixed member 117. The movement sequence then includes a coatingdelivery position shown in FIG. 5D where pad 116 is in physical contactwith and has a degree of compression with surface 119 of the fixedmember and the object to be coated. The coating delivery position servesto transfer the coating from pad 116 to the object. Preferably, object112 is placed closely adjacent to surface 119 of the fixed member sothat object 112 is not substantially deflected by the physical contactof pad 116 in the coating delivery position.

Preferably, the degree of compression of pad 116 in the coating loadingposition (t₂ /t₁) is greater than the degree of compression in thecoating delivery position (t₃ /t₁). In this embodiment, coating supplysystem 124 having coating reservoir 126 and a coating transport system128 perform similar functions as in the embodiment of FIGS. 1-3 as doesobject delivery system 134. Reciprocating member 114 preferably ismounted on a base 120 and includes a drive mechanism 130. Apparatus 110preferably includes a control system 132 to synchronize movement ofreciprocating member 114, movement of objects 112 and delivery of thecoating so that the amount of coating delivered to the object isprecisely controlled.

A preferred method for applying a coating to an object using apparatus110 is outlined in FIG. 6. The method includes having pad 116 away fromfixed member 117 in an initial rest position, moving the pad to acoating loading position against fixed member 117 and moving the padaway from the fixed member so that an object to be coated may be movedto a position intermediate to the pad and the fixed member. Thepreferred method then includes moving the pad to a coating deliveryposition where the pad is in physical contact and in a degree ofcompression with the object and the fixed member applying the coating tothe object. The pad is then moved away from the fixed member and thecoated object removed.

Other embodiments illustrated in FIGS. 7-12, are within the scope of thepresent invention. As shown in FIGS. 7-9, an apparatus 210 is used forcoating an object 212. Apparatus 210 includes a rotating member 250 witha porous resilient roll 216. Rotating member 250 rotates about a shaft251. Rotating member 250 has a rotary movement sequence schematicallyillustrated in FIG. 8. The movement sequence includes a coating loadingsegment where resilient roll 216 is in physical contact with and has adegree of compression with a coating loading member 260 The coatingloading member 260 preferably is supplied with coating by a coatingsupply system 224 which includes a coating reservoir 226 with a coating227 and a coating transport system 228. The coating loading member mayrotate counter to the rotation of rotating member 250 or it may befixed, but preferably, coating loading member 260 rotates counter tomember 250. Member 260 preferably is porous with the coating beingsupplied to a contact surface 262 of member 260 through a plurality ofpassageways 264 supplied by transport system 228. As resilient roll 216passes surface 262, the degree of compression may be determined bycomparing uncompressed thickness t₁ with thickness t₂ where roll 216contacts coating member 260. The t₂ /t₁ compression serves to transferthe coating to the resilient roll and spread it uniformly.

Apparatus 210 preferably further includes a base 220 and a rotatingsupport member 270 having a resilient surface 272. As resilient roll 216rotates past coating loading member 260 the compression is released androll 216 returns to uncompressed thickness t₁. Apparatus 210 preferablyincludes an object handling system 234 for moving objects 212 to becoated between resilient roll 216 and rotating support member 270 at thecoating loading segment so that resilient roll 216 is in physicalcontact and has a degree of compression with object 212 and surface 272of the rotating support member in an area 213. The compression betweenroll 216 and object 212 transfers the coating to the object. The degreeof compression between resilient roll 216 and surface 272 is shown bythickness (t₃ /t₁). Preferably the degree of compression in the coatingloading segment is greater than the degree of compression in the coatingdelivery segment.

A method for applying a coating to an object using the apparatus 210 ofthe present invention includes moving objects 212 between rotatingmember 250 which has porous resilient roll 216 with a loading of acoating mounted for rotatory motion about shaft 251 in a coatingdelivery segment so that the roll contacts resilient surface 272 onrotating support member 270 and object 212 with a degree of compression.

Control system 232 controls the coating delivery, the movement of therotating members and the object handling system.

As shown in FIGS. 10-11, an apparatus 310 for applying a coating to anobject 312 includes a pair of rotating members 350A, 350B mounted forcounter-rotatory movement so that the members contact each other duringone segment of the movement in an area of contact 313 and do not contacteach other at other segments of the movement. Rotating members 350A,350B rotate respectively about shafts 351A, 351B. Rotating members 350A,350B have a rotary movement sequence schematically illustrated in FIG.11. The movement sequence includes a coating loading segment where eachresilient roll 316A, 316B is respectively in physical contact and has adegree of compression with coating loading members 360A, 360B. Coatingloading members 360A, 360B may rotate counter to the rotation ofrotating member 350A, 350B or the coating loading members may be fixed,but preferably, coating loading members 360A, 360B rotate counter tomembers 350A, 350B. Members 360A, 360B preferably are porous with thecoating being supplied to contact surfaces 362A, 362B through aplurality of passageways 364A, 364B supplied by transport system 328A,328B. As resilient rolls 316A, 316B, respectively, pass surfaces 362A,362B, the degree of compression may be determined by comparinguncompressed thickness t₁ with thickness t₂ where rolls 316A, 316Bcontact coating members 360A, 360B. The compression t₂ /t₁ serves totransfer the coating to the resilient rolls and spread it uniformly intothe rolls.

Apparatus 310 preferably further includes a base 320 for mounting therotating members and the coating loading members. As resilient rolls316A, 316B rotate past coating loading members 360A, 360B, thecompression is released and rolls 316A, 316B return to the uncompressedthickness t₁. Apparatus 310 preferably includes an object handlingsystem 334 for moving objects 312 to be coated between the resilientrolls 316A, 316B in the direction of rotation of the rolls at theposition where the rolls are in physical contact with each other andhave a degree of compression. This movement of the objects between therolls causes the rolls to have a degree of compression with object 312being coated transferring coating from the rolls to the object.Preferably, the movement of objects 312 between resilient rolls 316A,316B is a continuous motion into and out of area of contact 313 of therolls. The degree of compression between the resilient rolls isdetermined by thickness t₃ /t₁. Preferably the degree of compassion inthe coating loading (t₂ /t₁) segment is greater than the degree ofcompression (t₃ /t₁) in the coating delivery segment.

A method for applying a coating to an object using the apparatus 310 ofthe present invention includes moving objects 312 between rotatingmembers 350A, 350B which has porous resilient rolls 316A, 316B with aloading of a coating. The rolls are mounted for counter rotatory motionabout shafts 351A, 351B in a coating delivery segment so that the rollscontact each other and the object being coated with a degree ofcompression.

The coating apparatus of the present invention may be compactly built tofit on assembly machines into space currently used for solvent basedcoating apparatus. The apparatus and method for its use demonstrate acapability to produce product having similar quality and performanceproperties to standard commercial product produced with solvent basedcoating. The apparatus of the present invention is also compatible withthe assembly rate requirements and efficiency of current assemblymachines using solvent based coating systems. The present inventionprovides a simple and reliable coating station for medical deviceassembly machines allowing manufacturers to eliminate the use of solventbased coating systems in many applications.

What is claimed is:
 1. An apparatus for applying a coating to an objectcomprising:a first reciprocating member including a drive mechanism, acoating feed system and a porous resilient pad; a second reciprocatingmember in opposing relationship to the first reciprocating memberwherein the second reciprocating member includes a drive mechanism, acoating feed system and a porous resilient pad; a coating supply systemoperatively connected to the first reciprocating member and the secondreciprocating member, the coating supply system including a reservoirand a delivery system for containing and supplying the coating to saidcoating feed systems; an object handling system for placing the objectin a position between said reciprocating members for coating, holdingthe object in said position during coating and removing the object aftercoating; a frame mounted to said first reciprocating member and saidsecond reciprocating member for motion toward and away from each other;a control system operatively connected to the object handling system,the first reciprocating member and the second reciprocating memberwherein the control system controls a movement sequence of said firstreciprocating member drive mechanism, said second reciprocating memberdrive mechanism, said object handling system and said coating supplysystem; said movement sequence comprising an initial rest positionwherein there is a space between said reciprocating members, a coatingloading position wherein said reciprocating members are in physicalcontact so that said resilient pads have a degree of compression witheach other for loading the coating, an intermediate rest positionwherein there is a space between said reciprocating members, a coatingdelivery position wherein said reciprocating members are in physicalcontact with each other and the object in said position for coating sothat said resilient pads have a degree of compression with each otherand the object thereby applying the coating to the object, said degreeof compression of said resilient pads in said coating loading positionbeing greater than said degree of compression of said resilient pads insaid coating delivery position, said movement sequence being completedby a return to said initial rest position; and said object handlingsystem including means for placing the object in said position forcoating between said reciprocating members when said reciprocatingmembers are in said intermediate rest position, holding the object insaid position for coating when said reciprocating members are in saidcoating delivery position and removing the object when saidreciprocating members are in said initial rest position.
 2. Theapparatus of claim 1 wherein each porous resilient pad includes abacking plate having a first side and a second side, and an reticulatedelastomeric foam having a front side and a back side, said back side ofsaid foam being fixedly attached to said first side of said backingplate, said backing plate having a plurality of holes therethrough fromsaid first side to said second side, said second side of said backingplate being in fluid communication with said coating supply system, sothat said coating is supplied to said back side of said foam, saidcoating loading position serving to distribute said coating in saidfoam.
 3. The apparatus of claim 2 wherein said backing plates have saidfirst sides facing each other in horizontal opposition, said foam beinga rectangular layer having a thickness between about 0.25 cm to about2.5 cm and about 300 to about 1250 pores per square centimeter; andsaidphysical contact of said pads being between said front sides of saidfoam with said degree of compression of said pads in said coatingdelivery position being less than said degree of compression of saidpads in said coating loading position.
 4. An apparatus for applyingsilicone lubricant to over-the-needle peripheral venous catheterscomprising:a pair of reciprocating members each comprising a porousreticulated elastomeric resilient foam pad mounted for movement towardand away from each other; a silicone supply system in communication withthe pair of reciprocating members for supplying silicone lubricant tosaid resilient pads; a control system operatively connected to the pairof reciprocating members to move the pair of reciprocating members froman initial rest position wherein said resilient pads are spaced apartfrom each other, to a lubricant loading position wherein said resilientpads are in physical contact and have a degree of compression with eachother thereby loading the lubricant on the pads, to an intermediate restposition wherein said resilient pads are spaced apart from each otherand so that a catheter to be lubricated is placeable between saidresilient pads, and finally to a lubricant delivery position whereinsaid resilient pads are in physical contact with each other and with thecatheter being lubricated, said pads having a degree of compression witheach other and the catheter to be lubricated in order to apply thelubricant to the catheter; and a catheter handling system operativelyconnected to the control system for placing the catheter in a positionbetween said reciprocating members for lubricating, holding the catheterin said position during lubrication and removing the catheter aftercoating.
 5. The apparatus of claim 4 wherein said catheter handlingsystem includes a holder for placing, holding and removing a pluralityof catheters.